An industrial robot of the general type here contemplated is known, for example, from U.S. Pat. No. 4,105,937. According to that patent, the free extremity of the robot arm can be fitted with a sensor including a tracing tip which is moved along a path conforming to the desired workpiece shape. The sensor emits a location signal to be stored in a memory of a programmer as an instruction for the guidance of a tool subsequently mounted on the robot arm in lieu of the sensor.
In many instances it is necessary to produce a number of workpieces of similar shapes differing only in minor structural details from one another. With conventional techniques, however, the program memory of the robot must be individually loaded for each type of workpiece on the basis of data obtained by the scanning of respective patterns with a sensor such as the tracing tip of the aforementioned U.S. patent. If the patterns have an intricate configuration, the sensor must have a large stroke relative to its supporting arm and the logical circuitry of the programmer will have to be rather complex.